Patent GB-1098721-A (GB)
Title: Improvements in or relating to roller door catches
Inventor: JAMES MICHAEL JOSEPH
IPC: E05C19/04
Filed: 1963-07-09
Abstract: 1,098,721. Catch fastenings. MICRO & PRECISION MOULDINGS (CHELTENHAM) Ltd. July 7, 1964 [July 9, 1963], No. 27064/63.. Heading E2A. A roller door catch comprises a roller carrying plunger 3 and housing I within which the plunger is reciprocable and from which the roller 6 projects under the influence of a return spring 7, adjustment means being provided within the housing which operate continually as a result of reciprocation of the plunger to effect adjustment of the outward projection of the roller. In the construction shown the adjustment means comprises a stop member 15 which is mounted on the plunger and engages a limit surface 19 fixed relatively to the housing to limit reciprocation in one direction the stop member being rotatable relatively to the plunger for the limit adjustment and arranged so that during reciprocation in the other direction it engages an adjustment surface 13 as a result of which the stop member can be rotated to adjust such limit, friction clutch means being arranged so that during reciprocation in said other direction the stop member is free to turn but as a result of engagement with said limit surface is restrained by the clutch means against further rotation after the clutch means becomes operative. Two of the adjustment surfaces 13 are provided, each of which is of part helical form spanning an arc of slightly less than 180‹ about the axis of reciprocation and moulded in the housing near the inner end. The plunger has a head 4 formed with a yoke in which the roller 6, which is barrel shaped, is rotatably mounted-and having a stem 5 which passes through a central bore 14 in a limit member 8 which is non-rotatably mounted in the housing 1 by means of projections 10 which engage guide ways 9 in the housing. It is axially located by the inner end faces 12 of the guideways 9 and is retained in the housing by lips on the projections 10 which snap into: apertures 22 in the wall of the housing 1; The spring: .7 is trapped between the limit member 8 and the head of thte plunger 3. The plunger 3 is guided in its sliding movement in the housing by the yoke arms of the head which engage the guideways 9. The limit member 8 is formed with two of the limit surfaces 19 which face inwards towards, and are complementary to, the adjustment surfaces 13. The stop member 15 is rotatably mounted on the inner end portion of the stem 5 and is retained thereon by a collet 16 engaged in a groove in the stem; the stop member 15 has limited degree of free axial movement between the shoulder 17 and the stem 5 and the collet 16 and has two radially projecting ears (not shown) for engagement with the surfaces 13 and 19. The friction clutch means which restrain rotation of the stop member 15 comprise a frusto-conical fixed clutch surface on the collet 16 which engages a complementary frusto-conical concave surface in the stop member 15; the collet 16 is prevented from turning by rib on the stem 5 which engages a radial split in the collet. In use, assuming that the plunger 3 is in its outermost possible position, the stop member ears 18 engage, under the action of the spring 7, the limit surfaces 19 at the outer ends thereof. On door closure, if the plunger 3 is displaced inwards only a short distance so that the ears 18 do not engage the adjustment surfaces 13, the plunger, 3 is returned by the spring to the original position when the door is next opened but if the plunger movement is greater than this the ears ride along the adjustment surfaces 13 thus turning the stop member 15 to a fresh angular position which limits return movement of the plunger 3 by engagement with: the limit surfaces 19 at intermediate positions thereon when the door is next opened; on inward movement of the plunger 3 the stop member 15 is relieved of spring loading and hence the clutch surfaces 23 and 24 are free to allow the stop member to turn on engagement with the adjustment surfaces. During return movement of the plunger a slight degree of clutch slip occurs between engagement of a stop member with the limit surfaces 19 and engagement of the clutch surfaces and this provides adjustment in the opposite direction since unless the return stroke of the plunger is limited by external means the stop member turns to a small extent when it engages the limit surfaces 19 and before the clutch is fully engaged and hence the outward movement of the plunger is slightly greater than the inward movement; adjustment in this manner continues curing successive plunger strokes until plunger movement outwardly is limited by external means.